Wednesday, September 21, 2005


This could be big!

Another great new technology is described here at Green Car Congress (sorry if this is old news to some of you, I'm still catching up on the past couple of weeks news...):

NexxtDrive DualDrive e-CVT Prototype Promises Fuel Savings, Hybrid Capability
14 September 2005



NexxtDrive (formally DriveTec UK), a UK-based design and development company, used the Frankfurt IAA to promote its prototype DualDrive, a power-split electronic Continuously Variable Transmission (e-CVT) with dual motor-generators.

NexxtDrive claims that the DualDrive can provide potential fuel and CO2 emissions savings of up to 20% even in non-hybrid applications. With the addition of a more robust energy storage and management system enabling full hybrid capabilities, NexxtDrive projects savings of up to 35%.

[Read the full article here]

As far as I understand this technology, it is a planetary gear box like the ones typically found in Toyota's 'Synergy' hybrid drivetrain. The DualDrive is very compact and so can easily replace the standard transmissions (manual or automatics) found in just about any car, which contrasts with existing planetary gear sets that have had to be specifically designed for each powertrain. This means that the DualDrive could be dropped into just about any car, including aftermarket retrofits of existing cars!

As far as I can tell, it raises fuel efficiency by using the planetary gear set to optimize torque at any speed so that you are always getting maximum (i.e. most efficient) power out of your engine (unlike normal transmissions which have ideal rpm 'power-bands' for various speeds but who's limited number of gear-ratios - typically only 4 or 5 - means you can't always get the ideal torque). Additionally, like the planetary gearbox in the Synergy drive, the DualDrive opens up the potential to easily couple it with full hybrid systems as it allows input from an ICE and/or electric batteries. Finally, it also replaces the conventional alternator and starter motor and can thus be used to integrate start-stop functionality (where the engine shuts off at idle and restarts instantaneously when coming out of idle) further boosting fuel efficiency in stop and go traffic.

It seems like these transmissions, if they are as good as they sound, should go (along with the TIGER exhuast to power system I discussed below and probably variable valve timing like in Honda's Accord hybrids) in every new car off the assembly line. This would also pave the way for a decrease in the cost and complexity of integrating hybrid systems and start-stop functionality into drivetrains. It seems to me like we should be seeing some kind of hybrid system in just about any kind of car in the relatively near future (5-10 years). We could easily make huge improvements in average transport fleet fuel efficiency, if the will (political/regulatory/consumer demand etc.) were there. Let's cross our fingers anyway... or better yet, contact your Congressman and support increased CAFE standards (see below)!

1 comment:

Anonymous said...

I get the feeling this is really something special and will be very interested to watch its progress in the industry. It is a great example of applying smart electronics to replace mechanical systems whereby the system characteristics become totally programmable. Looking at Nexxtdrive's site, the other huge development they touch on is the potential decoupling of an engine's compression and expansion processes, that could change a fundamental constraint of combustion engines since the beginning.